The present invention pertains to laminates, particularly electrical laminates.
Laminates have previously been prepared from bisphenol A based epoxy resins. It is known that the properties of a laminate can be improved by employing multifunctional epoxy novolac resins in the formulations. It is also known that just as significant as the improvements in laminate properties is the detrimental effect that multifunctional epoxy resins have on processability. The tris(hydroxyphenyl)methane, tetra(hydroxyphenyl)ethane and phenol-formaldehyde epoxy novolac resins have been unsuccessful toward this end because to achieve a glass transition temperature (Tg) of 150.degree. C. or higher, when cured with dicyandiamide, requires sufficient quantities of the multifunctional epoxy resin to have adverse effects in the following areas: (1) varnish reactivity, (2) prepreg reactivity, (3) prepreg cosmetics, (4) reinforcement wetability, (5) laminate pressing, (6) laminate post cure requirement and (7) blister resistance of the laminate.
It has now been discovered that these deficiencies can be overcome by the use of hydrocarbonphenol epoxy resins. They not only provide the electrical laminates prepared therefrom an improvement in electrical and moisture resistance properties, but they also provide an improvement in one or more of the above enumerated deficiencies.